Systems, Circuits, and Methods For Monitoring Solar Cells of an Adaptive Solar Power System

ABSTRACT

A back sheet comprises an interconnect circuit coupling a plurality of solar cell tiles. A tiled solar cell, comprising a solar cell and encapsulating and glass layers, is inserted into the solar cell tiles. Each solar cell is individually addressable through the use of the interconnect circuit. As such, each solar cell may be individually monitored through the utilization of the interconnect circuit of the back sheet.

RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.61/287,165 filed on Dec. 16, 2009 and entitled “An Adaptive Module forSolar Systems.”

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to the field of solar power systems,and more specifically towards systems, circuits, and methods formonitoring solar cells of an adaptive solar power system.

2. Art Background

Conventional solar modules are generally constructed by stringingtogether solar cells and then assembling the solar cells into a solarmodule that is typically encapsulated by ethylene vinyl acetate (EVA)and sandwiched between a glass sheet and a polyvinyl fluoride (TEDLAR)sheet. As such, a conventional solar module may comprise a packagedinterconnected assembly of solar cells. Monitoring of a conventionalsolar power system is generally performed at the solar module level bymeasuring each solar module's generated output. As such, anyreconfiguration of the conventional solar power system is conventionallyimplemented at the solar module level. The reconfiguration of solarmodules may be used to address issues that result when there exists apartial covering of a solar module. The partial covering of the solarmodule results in the degradation of the operating performance of thesolar module. Since the degraded solar module is typically in serieswith other solar modules to construct a solar module string, thedegradation of one solar module would adversely impact the performanceof the entire solar module string as the solar module string istypically limited by the weakest solar module.

Conventional reconfiguration techniques at the solar module level applytechniques for isolating each solar module from the solar module stringby using a DC-DC converter and then delivering the energy from the solarmodule. This results in each solar module operating independently.Typically, an external box is coupled to each solar module to controland implement the reconfiguration.

U.S. Pat. No. 6,350,944 discloses a reconfigurable solar panel systemcomprising a plurality of solar cells arranged in a predefined patternon a printed circuit board that comprises a predefined pattern ofinterconnection paths to form at least one solar cell module. The solarpanel is made of at least one solar cell module and has the capabilityto be configured and reconfigured by programming at least one integratedcircuit that communicates with each and every solar cell on the solarmodule. The system of U.S. Pat. No. 6,350,944 is capable of monitoring,controlling, and protecting the solar panel, as well as beingreconfigured before, during, and after the panel has been assembled.Moreover, U.S. Pat. No. 6,350,944 discloses a system for cell levelmonitoring of voltage measurements and cell level re-configurability.

Although conventional techniques provide systems and methods to monitorand reconfigure solar modules, it would also be advantageous to monitorand reconfigure individual solar cells. The increased granularity of themonitoring and reconfiguring would allow for a more flexible and robustsolar power system and provide means to harvest additional power.Additional techniques to implement a solar power system based on solarcells may eliminate the need for the conventional solar modulepackaging. As such, these techniques may additionally provide a moreflexible and robust solar power system.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth in the appendedclaims. However, for purpose of explanation, several embodiments of theinvention are set forth in the following figures.

FIG. 1 illustrates a solar power system architecture comprising a stringof solar cells.

FIG. 2 a illustrates an example of a solar cell architecture formonitoring the solar cell in accordance with some embodiments.

FIG. 2 b illustrates an example of a solar cell architecture formonitoring another type of solar in accordance with some embodiments.

FIG. 3 illustrates an example system architecture of a matrix ofindividually monitored solar cells.

FIG. 4 illustrates an example system architecture for cell monitoringand cell bypassing in accordance with some embodiments.

FIG. 5 a illustrates an example embodiment of switch fabric used in someembodiments of the system architecture.

FIG. 5 b illustrates a programmable switch used in some embodiments ofthe present invention.

FIG. 5 c illustrates the operation of an example programmable switchused in some embodiments of the present invention.

FIG. 6 illustrates an example embodiment of switch fabric configured toallow a series connection between solar cells.

FIG. 7 illustrates an example embodiment of switch fabric configured toexclude a solar cell from a series connection between solar cells.

FIG. 8 illustrates an example embodiment of the solar power systemarchitecture comprising programmable interconnect chips.

FIG. 9 illustrates a flow diagram for a method of monitoring andreconfiguring a solar cell.

FIG. 10 illustrates an example embodiment of a reconfiguration of solarcells in order to maximize energy output.

FIG. 11 is a flow diagram of a method for reconfiguring the solar cellsand programmable interconnect fabric to group solar cells of similaroutput efficiency into solar cell strings.

FIG. 12 illustrates an example embodiment of a back sheet integrationused in accordance with some embodiments.

FIG. 13 illustrates an example embodiment of a back sheet used inaccordance with some embodiments.

FIG. 14 illustrates an example embodiment of a back sheet implemented tomatch voltage specifications.

FIG. 15 illustrates an example embodiment of a solar cell used inaccordance with some embodiments.

FIG. 16 illustrates another example embodiment of a solar cell used inaccordance with some embodiments.

FIG. 17 illustrates an additional example embodiment of a solar cellused in accordance with some embodiments.

FIG. 18 illustrates an example embodiment of a control system used inaccordance with some embodiments.

FIG. 19 illustrates an example embodiment of an embedded softwarearchitecture used in some embodiments.

FIG. 20 is a flow diagram of a method of manufacturing a tiled solarcell in accordance with some embodiments.

FIG. 21 illustrates a flow diagram of a method of using an intelligentcleaning system for a solar power system.

FIG. 22 a illustrates the installation of conventional solar modules ona parcel of land.

FIG. 22 b illustrates an example embodiment of the installation of aback sheet with tiled solar cells onto a parcel of land.

FIG. 23 illustrates a flow diagram of a method of installing a backsheet with tiled solar cells in accordance with some embodiments.

DETAILED DESCRIPTION

The systems, methods, and circuits disclosed herein relate to anadaptive solar cell system. Specifically, the systems, methods, andcircuits relate to solar cell monitoring and reconfiguring by means oftiles and programmable interconnects on a back sheet.

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the presentinvention. However, it will become obvious to those skilled in the artthat the present invention may be practiced without these specificdetails. The description and representation herein are the common meansused by those experienced or skilled in the art to most effectivelyconvey the substance of their work to others skilled in the art. Inother instances, well known methods, procedures, components, andcircuitry have not been described in detail to avoid unnecessarilyobscuring aspects of the present invention.

FIG. 1 illustrates a solar power system architecture 100 comprising astring of solar cells. In general, the solar power system architecture100 comprises a plurality of solar cells, traces from the solar cells,and a junction box coupled to the traces from the solar cells.

As seen in FIG. 1, the solar power system architecture 100 comprises aplurality of solar cells 120, traces 121, bus lines 104, 105, and 106,pins 101, 102, and 103, and a junction box 110. Each solar cellcomprises at least one trace and each trace is coupled to a bus line.For example, solar cell 120 comprises a trace 121 that is coupled to busline 104. Each bus line 104, 105, and 106 is coupled to a pin 101, 102,or 103. Each solar cell trace is subsequently accessible from the pins101, 102, or 103 to a junction box 110.

FIG. 2 a illustrates a solar cell system architecture 200 for monitoringa solar cell. In general, the solar cell system architecture 200comprises a solar cell that may be individually addressed and monitored.

As seen in FIG. 2 a, the solar cell system architecture 200 comprises asolar cell 205. In some embodiments, the solar cell 205 comprises aconventional solar cell. In the same or alternative embodiments, thesolar cell 205 may comprise a back contact solar cell. For example, FIG.2 b illustrates a solar cell system architecture 210 comprising aconventional solar cell 211. As such, the monitoring and reconfiguringof a solar cell 205 may not depend on the type of solar cell 205 that isimplemented in the solar cell system architecture 200. In someembodiments, the solar cell system architecture 200 comprises a columnselector 201, row selector 202, and metal oxide semiconductorfield-effect transistors (MOSFETs) 203 and 204. The row selector 202 maybe coupled to the gates of each of the MOSFETs 203 and 204 while thecolumn selector 201 may be coupled to the source or drain of each of theMOSFETs 203 and 204.

In operation, some embodiments of the solar cell system architecture 200of FIG. 2 a comprise a row selector 202 and a column selector 201. Therow selector 202 may be configured for enabling a solar cell. Forexample, if the row selector 202 enables the solar cell 205, then theMOSFETs 203 and 204 are also enabled. Next, the column selector 201 maybe configured to measure the current and/or the voltage across the solarcell. As such, the MOSFETs 203 and 204 enable a voltage measurement tobe taken across the solar cell 205.

FIG. 3 illustrates an example of an architecture of a matrix 300 ofindividually monitored solar cells. In general, the matrix 300 comprisesa plurality of solar cells 306 and associated traces arranged in rowsand columns. Each of the solar cells 306 within the matrix 300 may beindividually monitored through the use of the row selector 302 andcolumn selector 301.

As seen in FIG. 3, the matrix 300 comprises a plurality of solar cells306. Each solar cell 306 may be coupled to a plurality of MOSFETs 303,304, and 305. The matrix 300 further comprises a row selector 302 and acolumn selector 301. Each solar cell 306 may be coupled to MOSFETs (orswitches) 303, 304, and 305 that may be enabled for sampling of thesolar cell's voltage and/or current. In some embodiments, a row selectormay enable a set of solar cells 306 connected to one row. For example,the row selector 302 may enable MOSFETs 303, 304, and 305 of each solarcell 306 of solar cell row 310. In this instance, solar cells of solarcell rows 311 and 312 would not be enabled. Next, the column selector301 may measure voltages and/or currents for each of the enabled solarcells from solar cell row 310. In some embodiments, the column selector301 may implement a clocking scheme for walking through each solar cellof a selected solar cell row 310, measuring the voltage and/or currentof each solar cell, and then transmitting the voltage and/or currentdata and/or solar cell address to a processing unit, as discussed below.

In some embodiments, the above disclosed monitoring functions areperformed by a monitoring circuit. For example, the monitoring circuitmay comprise a sampling circuit for sampling voltage levels at the solarcells 306. In some embodiments, the sampling of the voltage levels maybe performed as a function of time with a certain periodicity andinterval time between sampling periods. For example, the monitoringcircuit may control sampling of solar cells 306 so that the solar cells306 are sampled at least twice per day. In some embodiments, themonitoring circuit may comprise a tuned sampling accuracy for a specificmonitoring application.

As such, the matrix 300 of FIG. 3 comprises a plurality of solar cellsthat may comprise conventional solar cells and/or back contact solarcells. Row selectors may enable a row of solar cells and a columnselector may step through and monitor the voltage and current of eachsolar cell enabled in a selected row.

FIG. 4 illustrates an example of a solar cell matrix 400 capable ofmonitoring and/or bypassing solar cells. In general, the solar cellmatrix architecture 400 comprises a plurality of solar cells. Each solarcell is capable of being individually addressed and monitored as well ascapable of being individually bypassed. In some embodiments, the abilityof the solar cell matrix 400 to output energy is limited by the weakestsolar cell comprised within the solar cell matrix 400. As such, in someembodiments, a solar cell may be bypassed when the performance of thesolar cell is out of specification. Thus, the bypassing of the solarcell may allow a more optimal performance for the solar cell matrix 400.This type of approach may be termed “harvesting by cell exclusion” asspecific solar cells may be bypassed and isolated from other solar cellswithin the solar cell matrix 400.

As seen in FIG. 4, the solar cell matrix 400 comprises a plurality ofsolar cells 430 arranged in rows and columns, row selector 420, andcolumn selector 410. The solar cell matrix 400 further comprises aplurality of MOSFETs or switches coupled to each solar cell 430. MOSFETs425, 440, and 445 are implemented so as to allow for the monitoring ofeach individual solar cell 430, as discussed with relation to FIG. 3. Assuch, the row selector 420 may select a row of solar cells and enablethe solar cells within the row and the column selector 410 may stepthrough and monitor the voltage and current of each solar cell enabledin a selected row. Solar cell matrix 400 comprises an additional MOSFET(or switch) 435 for purposes of bypassing a solar cell. In someembodiments, the MOSFET 435 is placed across the solar cell 430. Inother embodiments, the MOSFET 435 is comprised within the solar cell435. As such, in the solar cell matrix 400, each solar cell may comprisea MOSFET 435 placed across each individual solar cell. The MOSFET 435may be used to bypass the solar cell 430 such that the energy outputfrom the solar cell 430 is not collected.

In some embodiments, the solar cell matrix 400 of FIG. 4 may temporarilyenable a bypass switch or MOSFET 435. For example, one solar cell 430may be partially shaded or covered by debris. Enabling the bypass switchor MOSFET 435 of the partially shaded or covered solar cell 430 mayallow the solar cell matrix 400 to operate a higher performance sincethe overall solar cell matrix 400 is no longer limited by the partiallyshaded or covered solar cell 430. In some embodiments, once the solarcell 430 is no longer partially shaded or covered so that the solar celldoes not limit or degrade the overall performance of the solar cellmatrix 400, the bypass switch or MOSFET 435 may be disabled so that thesolar cell 430 is no longer bypassed.

In some embodiments, a two terminal device such as a diode may beimplemented in place of the bypass switch or MOSFET 435. However, insome embodiments, control of the diode from an external module orcontrol system may be difficult.

FIG. 5 a illustrates programmable interconnect fabric 500 used in someembodiments of the solar cell matrix architecture that has beendescribed above. In general, the programmable interconnect fabric 500comprises at least one programmable switch that may be used to rerouteand capture the energy that has been produced by a solar cell that hasbeen bypassed.

As seen in FIG. 5 a, the programmable interconnect fabric 500 connects aplurality of solar cells. For example, the programmable interconnectfabric 500 connects a solar cell 520 with a solar cell 530. Moreover,the programmable interconnect fabric 500 comprises at least oneprogrammable switch 510 that may be used to route energy produced by thesolar cells.

FIG. 5 b illustrates a programmable switch 510 that may be used in someembodiments of the programmable interconnect fabric 500. As illustrated,the switch 510 comprises a state 520 and a state 515. The switch 510 maybe programmed to be placed in a state 520 and thus couple the routingsegment 525 to the routing segment 540. Alternatively, the switch 510may be placed in a state 515 and thus couple the routing segment 525 tothe routing segment 530.

FIG. 5 c illustrates another embodiment of a programmable switch 510that may be used in the programmable interconnect fabric 500. Asillustrated, the switch 510 comprises a routing segment 580, routingsegment 590, and states 560 and 570. The switch 510 may be programmed tobe placed in a state 560, which would couple routing segment 580 torouting segment 590 and thus allow energy or current to flow fromrouting segment 580 to routing segment 590. In some embodiments, thiswould be described as an “on” state for the switch 510. Alternatively,the switch 510 may be placed in an “off” state 570. In an “off” state570, the routing segment 580 is not coupled to the routing segment 590.As such, in an “off” state 570, current or energy does not flow from therouting segment 580 to the routing segment 590.

As a result, the programmable switches may be used to route currentthrough the programmable interconnect fabric 500 and to couple at leastone solar cell to another solar cell. As such, the programmableinterconnect fabric 500 comprising programmable switches 510 may beimplemented to control the current flow from a solar cell. In someembodiments, the programmable interconnect fabric 500 may be configuredso as to allow a series connection from a solar cell to a neighboringsolar cell. As such, the programmable interconnect fabric 500 may beprogrammed to achieve a standard solar cell string connection. In someembodiments, the programmable interconnect fabric 500 may be configuredso as to bypass a solar cell that is performing out of specification. Assuch, the programmable interconnect fabric 500 may perform an exclusionconnection of a solar cell within a solar cell matrix. In someembodiments, the programmable interconnect fabric 500 may further beprogrammed to reroute current or energy from a bypassed solar cell to aparallel bus route, as discussed in further detail below. In someembodiments, multiple bypassed cells may be configured to be connectedin series. In the same or alternative embodiments, the parallel busroute(s) may be combined to another bus route in order to integrate theoutputs.

FIG. 6 illustrates an example embodiment of a configuration 600 ofprogrammable interconnect fabric to allow a series connection betweensolar cells in a solar cell matrix. As illustrated, a solar cell matrixcomprises a plurality of solar cells 610, 620, and 630. The programmableinterconnect fabric comprises a bus 604, parallel bus 605 and aplurality of programmable switches. In this embodiment, programmableswitches 640 are enabled so as to allow a series current to flow betweensolar cells 610, 620, and 630. As a result, there is no bypassing of asolar cell 610, 620, or 630 and current from each of the solar cells610, 620, and 630 is flowing in series.

FIG. 7 illustrates an example embodiment of a configuration 700 ofprogrammable interconnect fabric configured to bypass a solar cell andreroute the bypassed solar cell output to a parallel bus. Asillustrated, a solar cell matrix may, in some embodiments, comprisesolar cells 710, 720, and 730. The programmable interconnect fabric maycomprise a bus 704, parallel bus 705, and a plurality of switches. Inthis embodiment, the programmable switches 740 are enabled so as toallow the current from solar cell 710 and the current from solar cell730 to flow together in series. In some embodiments, the series currentfrom these solar cells is routed through bus 704. However, solar cell720 has been bypassed. Although solar cell 720 has been bypassed, it maystill be capable of producing a current. As such, the output currentfrom bypassed solar cell 720 is routed to parallel bus 705. Thus, energyis collected from each of the solar cells 710, 720, and 730. In someembodiments, outputs from each bus or parallel bus line may be combined.

FIG. 8 illustrates an example embodiment of a solar cell matrix 800 withprogrammable interconnect fabric that comprises at least one embeddedprogrammable chip. As illustrated, the solar cell matrix 800 comprises aplurality of solar cells 820, at least one embedded programmableinterconnect chip 830, parallel bus 810, and bus 815. In someembodiments, the embedded programmable interconnect chip 830 determinesthe routing of current between solar cells 820 and through theprogrammable interconnect fabric. In some embodiments, the embeddedprogrammable interconnect chip 830 comprises at least the functionalityof the switches described with relation to FIGS. 5 b and 5 c.

In some embodiments, the embedded programmable interconnect chip 830 maycomprise the routing functionality to allow a series connection throughsolar cells, bypass a solar cell, and/or bypass a solar cell andre-route the energy from the bypassed solar cell to parallel bus 810.Although the embedded programmable interconnect chip is illustrated asbeing a part of the programmable interconnect fabric, in someembodiments the embedded programmable interconnect chip 830 may beintegrated onto each solar cell 820. As such, in some embodiments, theembedded programmable interconnect chip 830 may be fabricated onto thesolar cell 820. This may result in the elimination of separate discretedevices, such as the embedded programmable interconnect chip 830, frombeing integrated into the programmable interconnect fabric.

FIG. 9 is a flow diagram for the monitoring and reconfiguration of asolar cell in accordance with some embodiments. In general, each solarcell of a solar cell matrix may be monitored and reconfigured. At block910, at least one solar cell is enabled. In some embodiments, the solarcells are arranged in rows and columns so as to comprise a solar cellmatrix. In this embodiment, a row selector module may enable a row ofsolar cells such that every solar cell within the row is enabled. Insome embodiments, an individual solar cell of a plurality of solar cellswithin a single row of a solar cell matrix may be enabled. At block 920,measurements of each enabled solar cell are taken and received. In someembodiments, the measurements comprise a solar cell's voltage and/orcurrent output. In the same or alternative embodiments, a columnselector module implements a clocking scheme to measure pairs of solarcell voltages across a precision resistor in order to measure thevoltage output of a solar cell. Thus, in some embodiments, a solar cellvoltage may be used as a proxy for the energy that is being generated bythe solar cell. At block 930, an output of at least one sensor may bereceived. In some embodiments, the sensor may be comprised within theback sheet. In the same or alternative embodiments, the sensor may becomprised within the solar cell. In other embodiments, the sensor may becomprised within a control system module. The sensor output may indicatethe ambient conditions within a solar cell or within an area of the backsheet. In some embodiments, a sensor may measure or record conditionssuch as, but not limited to, temperature, humidity, and irradiance.

At block 940, the measurements from block 920 and the sensor outputsfrom block 930 may be processed. In some embodiments, the data withregard to each enabled solar cell's voltage and sensor outputs may belogged with a timestamp. The data may then be algorithmically processedto determine whether the cell is performing within certainspecifications. At block 950, a determination is made whether the solarcell is within specification. If the solar cell is within specificationthen, at block 960, no reconfiguration is performed and the method ends.If the solar cell is not within specifications then, at block 970, thesolar cell may be reconfigured. In some embodiments, the solar cell isreconfigured by excluding or bypassing the solar cell from other cellsin the solar cell matrix. In this embodiment, the output from thebypassed solar cell may be routed to a parallel bus so that the energyfrom the bypassed solar cell is harvested without impacting the othersolar cells that are within the specifications.

FIG. 10 illustrates an example embodiment of a reconfiguration 1000 ofsolar cells in a solar cell matrix in order to maximize energy output.As described earlier, a solar cell may be in series with other solarcells to construct a solar cell string. This is due to charge sharingamong solar cells where a solar cell generating more energy transfersenergy to a neighboring cell that is generating a lesser amount ofenergy. As such, the amount of energy driving the output load of thesolar cell string is reduced. Thus, the degradation of one solar cell ofa solar cell string may adversely impact the performance of the entiresolar string as the solar cell string is typically limited by theweakest solar cell in the string.

As illustrated in FIG. 10, a back sheet 1010 comprises solar cells 1020,1030, 1050, and 1060. Solar cells 1050 and 1060 comprise a 100% output.However, solar cells 1020 and 1030 have degraded and may comprise a 50%output. As such, if a solar string comprised solar cells 1020 and 1030with a 50% output and the solar cells 1050 and 1060 with a 100% output,then the solar cell string would be limited or reduced by the 50% outputof the solar cells 1020 and 1030. As such, in some embodiments, theprogrammable interconnect fabric is configured so that degraded solarcells are in series with other degraded cells and fully functioningsolar cells are connected in series with other fully functioning solarcells. For example, solar cell 1020 and solar cell 1030, each with a 50%output, are connected in series by programmable interconnect fabricroute 1040. As such, solar cell 1020 and solar cell 1030 comprise asolar cell string. However, solar cell 1050 and solar cell 1060, eachwith a 100% output, are comprised in a separate solar cell string. Forexample, solar cell 1050 is connected in series with solar cell 1060 byprogrammable interconnect route 1070. As a result, FIG. 10 illustratestwo solar cell strings implemented in a single back sheet, each solarcell string comprising solar cells of similar output efficiency. As aresult, the solar cell strings will not display output energy loss dueto solar cell mismatches.

Although the above illustration and description shows thereconfiguration of four solar cells to construct two solar cell strings,it should be appreciated that any number of solar cells may bereconfigured to create any number of solar cell strings.

FIG. 11 illustrates a flow diagram of a method 1100 for reconfiguringthe solar cells and programmable interconnect fabric to group solarcells of similar output into solar cell strings. In general, the method1100 reconfigures solar cells and programmable interconnect fabric sothat solar cells of similar output may be connected in series toconstruct a solar string.

As illustrated in FIG. 11, at block 1110, the output of solar cells ismeasured. For example, solar cells may be measured to determine thosesolar cells that are operating within a defined specification and thosesolar cells that are operating out of a defined specification. Forexample, as solar cells age, each solar cell may age differently. Thus,a measured current-voltage (IV) curve or characteristic of the solarcells will diverge. At block 1120, the solar cells may be categorizedinto groups of solar cells of a similar output. For example, if a backsheet comprises two solar cells operating at a 100% output and threesolar cells operating at a 50% output, then the two solar cellsoperating at a 100% output may be categorized into a first group ofsolar cells and the three solar cells operating at a 50% output may becategorized into a second group of solar cells. At block 1130, the solarcells in each group are evaluated with respect to each other solar cellin the group to determine if any of the solar groups are located in aposition of the back sheet such that the distance between solar cellscreates energy inefficiencies. For example, if one of the solar cells ofthe second group comprising the three solar cells at a 50% output islocated at a significant distance from the other two solar cells at a50% output, then the distance between the solar cells may create energyinefficiencies due to the longer required interconnect path between thesolar cells. As such, in some embodiments, solar cells that aredetermined to be of longer distance to other solar cells may be removedfrom a grouping of solar cells. As such, the solar cell that is toodistant from the other solar cells will not be comprised within thesolar string comprising the other cells of similar output.

As seen in FIG. 11, at block 1130, a determination is made whether asolar cell is too distant from other solar cells within a grouping. Ifthe solar cell is not too distant, then at block 1140, a solar cellstring is created. In some embodiments, the solar cell string is createdby reconfiguring solar cells and the programmable interconnect fabricsuch that the solar cells are connected in series with each other.However, if the solar cell is too distant from the other solar cellswithin a grouping of solar cells, then the distant solar cell will beremoved from the grouping. Then, at block 1160, a solar cell string iscreated for the remaining solar cells. As such, in some embodiments, thesolar cell string is similarly created by reconfiguring solar cells andthe programmable interconnect fabric such that the solar cells areconnected in series with each other.

As a result, the method 1100 of FIG. 11 provides for the discriminationof solar cells based on the solar cell output efficiency. In someembodiments, the solar cells are discriminated based upon IV performanceand spatial positioning of solar cells. In some embodiments, every solarcell's output is measured. The solar cells may then be grouped accordingto output measurements. In some embodiments, a deviation from aspecification may be specified. For example, solar cells that deviate0.1% to 2% from a specified output level may be grouped into a firstsolar cell string and solar cells that deviate 2% to 3% from thespecified output level may be grouped into a second solar cell string.In some embodiments, distance between solar cells may be used to excludea solar cell from a solar cell string. For example, if a group containssolar cells that deviate 1% to 3% from a specified output level aregrouped, any solar cells that are at a defined distance or a distancecalculated to create an energy inefficiency or loss due to interconnectlength between solar cells may be excluded from the group. As such, thedistant solar cell may be comprised within a separate solar cell string.In some embodiments, solar cells may be grouped by geographic locationwithin a solar cell matrix and then solar cells of similar output withinone geographic location may be grouped into a solar cell string. In someembodiments, a model may be used to determine whether to include solarcells into a solar cell string. In some embodiments, the solar cellstrings may be created so as to meet a voltage specification, asdiscussed in more detail below.

FIG. 12 illustrates an example embodiment of a back sheet integration1200 used in accordance with some embodiments. In general, the backsheet integration 1200 comprises a back sheet 1210 and tiled solar cells1220, 1230, and 1240. In some embodiments, the back sheet 1210 comprisesa current carrying grid, programmable interconnect fabric, andprogrammable switches. The tiled solar cells 1220, 1230, and 1240 maycomprise a solar cell with various materials stacked around the solarcell. As illustrated, the back sheet 1200 is configured to containgrooves 1270, 1280, and 1290, or cell tiles, into which the tiled solarcells 1220, 1230, and 1240 may be easily inserted. As such, the backsheet 1210 may be integrated with individual tiled solar cells 1220,1230, and 1240. In some embodiments, a tedlar layer 1211, anencapsulation (EVA) layer 1212, EVA layer 1213, and a glass layer 1214may be coupled to the back sheet 1210. Further details with regard tothe back sheet 1210 and the tiled solar cells 1220, 1230, and 1240 arediscussed in further detail below.

FIG. 13 illustrates an example embodiment of a back sheet 1300 used inaccordance with some embodiments. In general, the back sheet 1300comprises cell tiles arranged in rows and columns such that tiled solarcells may be inserted into the cell tiles of the back sheet 1300.

As illustrated in FIG. 13, the back sheet 1300 comprises a plurality ofcell tiles 1340, current carrying grid 1350 for connecting the celltiles 1340, and programmable electronics 1360. In some embodiments, theprogrammable electronics 1360 comprise programmable interconnects orswitches, as described above. The current carrying grid 1350 couples thecell tiles 1340. Moreover, tiled solar cells (discussed below) may beinserted into the cell tiles 1340. For example, the cell tiles 1340 ofthe back sheet 1300 may accompany mechanical holders that secureinserted tiled solar cells. In some embodiments, turning the tiled solarcell in one direction when inserted into the back sheet 1300 may securethe tiled solar cell into the cell tile 1340. In the same embodiment,turning the inserted and secured tiled solar cell in the oppositedirection may release the tiled solar cell from the cell tile 1340. Theback sheet 1300 may further be coupled to a row selector 1330, addressselector 1320, and control system 1310 to perform the monitoring andreconfiguration processes as discussed above.

As such, the back sheet with integrated tiled solar cells eliminates theneed for a conventional solar module for housing solar cells. Theelimination of the conventional solar module for housing solar cells andreplacement of the solar module with the back sheet 1300 withindividually tiled solar cells for insertion into cell tiles 1340provides numerous advantages, as discussed in further detail below.

FIG. 14 illustrates an example embodiment of a back sheet 1400implemented with tiled solar cells to match voltage specifications. Ingeneral, the back sheet 1400 may string together any number of celltiles 1420 with interconnect 1410 between cell tiles 1420. In someembodiments, a tiled solar cell inserted into a cell tile 1420 maygenerate a predefined voltage output. As such, the number of cell tilesin a back sheet may be numbered to match a desired voltage output. Thus,the back sheet 1400 may be able to support variable voltage standards.

As discussed earlier, conventional solar power systems comprise the useof solar modules. As such, the level of granularity for the conventionalsolar power system is at the level of the solar modules. As a result, ifeach solar module comprises a 100 volt output and the solar power systemneeds to meet a 680 volt output specification for insertion into aninverter, then only six solar modules may be used due to voltagespecifications. This is because the conventional solar power systemoperates at a granularity level of solar modules. However, reducing thelevel of granularity to solar cells, or tiled solar cells, allows for acloser matching of the output specification.

As illustrated in FIG. 14, a back sheet 1400 comprises a number of celltiles 1420. The cell tiles 1420 are arranged in strings withinterconnects 1410 coupling cell tiles 1420 in a string. The number ofcell tiles 1420 may be variable. For example, if a 1000 volt output isneeded and if each cell tile 1420 with an inserted tiled solar cellgenerates a 0.5 volt output, then a string with 2000 cell tiles wouldgenerate a 1000 output voltage. Although an example of 2000 cell tilesgenerating a 100 output voltage is provided, it should be appreciatedthat the use of the back sheet with cell tiles can be used to meet anyvariable voltage standard. Moreover, solar cell strings may be createdto connect solar cells in series in such a way to match a voltagestandard. For example, if a 1500 voltage output is specified and eachsolar cell comprises a 0.5 voltage, then a solar cell string comprises3000 solar cells may be created.

FIG. 15 illustrates an example embodiment of a tiled solar cell 1500that may be used in conjunction with some embodiments of the back sheet.As illustrated, the tiled solar cell is comprised of a stack of variousmaterials and components. A glass layer 1510 may be stacked on top of anencapsulation material. In some embodiments, the encapsulation material1520 comprises ethylene vinyl acetate (EVA). The glass layer 1510 andencapsulation layer 1520 are stacked on top of the solar cell 1530. Asecond encapsulation layer 1540 is stacked immediately below the solarcell 1530. In some embodiments, the second encapsulation layer 1540comprises an EVA material. A TEDLAR (polyvinyl fluoride) layer 1550 maybe stacked below the second encapsulation layer 1540. The tiled solarcell may further comprise a pair of cell pins 1570 coupled to theencapsulated solar cell and protruding out of the TEDLAR layer 1550. Insome embodiments, the cell pins 1570 are used to connect to a busbarand/or the current carrying grid of the back sheet. The tiled solar cellmay further comprise an edge sealant 1560 on each edge of the tiledsolar cell 1500. In some embodiments, the tiled solar cell stack may belaminated just as a solar module is laminated after a bonding step. Assuch, in some embodiments, each solar cell 1530 within the tiled solarcell 1500 is protected in a similar manner as solar cells within aconventional solar module.

Thus, the tiled solar cell 1500 of FIG. 15 is an individually tiledsolar cell such that the tiled solar cell may be placed into a backsheet. The tiled solar cell 1500 may be individually inserted or removedfrom the current carrying grid of a back sheet. For example, the tiledsolar cell may be inserted into a groove or cell tile in the back sheetand turned to make a connection with the current carrying grid of theback sheet. Moreover, the same tiled solar cell may be removed simply byturning the tiled solar cell in the opposite direction. In someembodiments, the cell pins 1570 are configured to make an electricalcontact with the current carrying grid comprised within the back sheetwhen the tiled solar cell 1500 is inserted into the back sheet. In thesame or alternative embodiments, the cell pins 1570 make frictionalcontact with the current carrying grid of the back sheet. The contactresistance between the tiled solar cell 1500 and the current carryinggrid of the back sheet may be matched to prevent loss of energy in theform of heat dissipation. Thus, the tiled solar cells are easily pluggedin and pulled out of the back sheet.

FIG. 16 illustrates another example embodiment of a tiled solar cell1600 used in accordance with some embodiments. In general, the tiledsolar cell 1600 comprises a glass layer on the top and bottom sides ofthe tiled solar cell 1600. As illustrated, the tiled solar cell 1600 isalso comprised of a stack of various materials and components. A glasslayer 1610 may be stacked on top of an encapsulation material 1620. Insome embodiments, the encapsulation material 1620 may also compriseethylene vinyl acetate (EVA). The glass layer 1610 and encapsulationlayer 1620 are stacked on top of a solar cell 1630. A secondencapsulation layer 1640 is also stacked immediately below the solarcell 1630. In some embodiments, the second encapsulation layer 1640 alsocomprises an EVA material. However, unlike the tiled solar cell 1500, asecond glass layer 1650 is located at the bottom of the tiled solar cell1600. The tiled solar cell may also further comprise a pair of cell pins1670 coupled to the encapsulated solar cell 1630 and protruding out ofthe glass layer 1650. The tiled solar cell may further comprise edgesealants 1660 on each edge of the tiled solar cell 1600. As such, insome embodiments, each solar cell 1630 within the tiled solar cell 1600is protected in a similar manner as solar cells within a conventionalsolar module that comprises solar cells. Moreover, the addition of thesecond glass layer 1650 instead of the TEDLAR layer of the tiled solarcell 1500 increases the robustness of the tiled solar cell 1600.Additionally, the glass layer 1650, located at the back of the tiledsolar cell 1600, may provide the mechanical rigidity required for busbarleads to provide frictional contact with the current carrying gridcomprised within the back sheet.

The tiled solar cell 1600 of FIG. 16 may also be an individually tiledsolar cell such that the tiled solar cell may be placed into a backsheet, as discussed above with relation to the tiled solar cell 1500. Assuch, the tiled solar cell 1600 may also be individually inserted orremoved from the current carrying grid of a back sheet in the samemanner as the tiled solar cell 1500.

FIG. 17 illustrates another example embodiment of a tiled solar cell1700 used in accordance with some embodiments of a solar power system.In general, the tiled solar cell 1700 comprises a glass layer on thebottom or back side and the front side or top layer comprises a polymer.

As illustrated in FIG. 17, the tiled solar cell 1700 is also comprisedof a stack of various materials and components. An encapsulation layer1710 may be stacked on the top, or front, of a tiled solar cell 1700. Insome embodiments, the encapsulation material 1710 may comprise ethylenevinyl acetate (EVA). In this embodiment, the encapsulation layer 1710 isplaced immediately on top of a solar cell 1730. Below the solar cell1730 is a second encapsulation layer 1730. In some embodiments, thesecond encapsulation layer 1730 also comprises an EVA material.Moreover, a glass layer 17600 is located at the bottom of the tiledsolar cell 1600 immediately below the second EVA layer 1730. The tiledsolar cell may also further comprise a pair of cell pins 1750 coupled tothe encapsulated solar cell 1720 and protruding out of the glass layer1760. The tiled solar cell 1700 may further comprise edge sealants 1740on each edge of the tiled solar cell 1700. As such, in some embodiments,each solar cell 1720 within the tiled solar cell 1700 is protected injust as solar cells within a conventional solar module are protected. Assuch, the tiled solar cell 1700 only comprises a glass layer 1760 on theback side of the tiled solar cell 1700. The back side glass layer 1760also provides needed rigidity to the tiled solar cell 1700 and serves toprovide mechanical rigidity needed for busbar leads. Moreover, the frontside or top of the tiled solar cell 1700 comprises the encapsulationlayer 1720, which allows the solar cell 1730 to be exposed to sunlight.

The tiled solar cell 1700 of FIG. 17 may also be an individually tiledsolar cell such that the tiled solar cell may be placed into a backsheet, as discussed above with relation to the tiled solar cell 1500 andtiled solar cell 1600. As such, the tiled solar cell 1700 may also beindividually inserted or removed from the current carrying grid of aback sheet in the same manner as the tiled solar cell 1500 and tiledsolar cell 1600.

In some embodiments, the tiled solar cells disclosed above may comprisean optically tuned glass layer in order to realize concentratedphotovoltaic (CPV) cells. Since the tiled solar cells may comprise aglass layer with optical properties embedded in the glass layer, thetiled solar cell may function as a CPV cell handling multiple lightsources focused on the tiled solar cell. As such, when the tiled solarcells are arranged into a solar cell matrix on a back sheet, the solarcell matrix may be composed of optically charged (CPV) tiled solar cellsfor an increased performance.

FIG. 18 illustrates an example embodiment of a control system for themonitoring and reconfiguration of solar cells used in accordance withsome embodiments of the present invention. In general, in someembodiments, the control system comprises a printed circuit board (PCB)that may comprise various modules and components. In the same oralternative embodiments, the PCB is integrated into a junction box thatis attached to a back sheet and configured to receive measurements andsensor outputs from each of the enabled solar cells that have beeninserted into the back sheet. In some embodiments, the junction box maybe thermally managed.

As illustrated in FIG. 18, a control system 1800 may comprise variouscomponents, modules, and/or connections. For example, the control system1800 may comprise a processor 1810. In some embodiments, the processor1810 is a microprocessor configured to make determinations based on thestate of the solar cells by examining measurements and sensor outputs.The control system 1800 may further comprise a selecting and measuringmodule 1820 that is configured to receive data from the solar cellsinstalled on the back sheet. In some embodiments, the selecting andmeasuring module 1820 comprises a row selector and measuring deviceselector. The selecting and measuring module 1820 is coupled to theprocessor 1810 in order to send data to the processor. The controlsystem 1800 may further comprise a memory bank 1830 that is coupled tothe processor 1810. In some embodiments, the memory bank 1830 may storedata or log information that has been processed by the processor 1810.The control system 1800 may further comprise a communications interface,coupled to the processor, for communicating with a server (not shown)over a connection 1880. Some embodiments of the control system 1800 mayfurther comprise additional peripherals 1850 to provide variousfunctions with regard to the monitoring and reconfiguring of solar cellsinstalled on a back sheet.

In operation, the control system 1800 of FIG. 18 generally monitors andreconfigures individual solar cells that have been installed into a backsheet comprising a current carrying grid. In some embodiments, a singlecontrol system 1800 is coupled to or installed within a back sheet andmay be capable of monitoring and reconfiguring every individual solarcell that has been installed into the back sheet. As a result, a singlecontrol system 1800 may control all solar cell monitoring andreconfiguring for an entire back sheet comprising a plurality of solarcells. The control system 1800 may be coupled to a connector orinterconnect of the back sheet such that the control system 1800 mayhave access to electrical traces to each of the solar cells. As such,the control system 1800 may receive monitoring information and sensoroutputs for each individual solar cell on the back sheet.

The selecting and measuring device 1820 may select or enable anindividual solar cell or an entire row of a solar cell matrix formeasuring the solar cell's voltage and/or current, as discussed above.In some embodiments, the selecting and measuring device 1820 may alsomonitor sensor outputs that may measure the irradiance, humidity, and/ortemperature of the individual solar cell, group of solar cells, or theback sheet. The measurement data, which may comprise, but is not limitedto, any or all of a measured voltage, current, irradiance, humidity, ortemperature, is then transmitted to the processor 1810. In someembodiments, the processor 1810 is configured to make determinations ofa solar cell based on the state of the solar cell. For example, theprocessor 1810 may make a determination based on the measured values ofcurrent, voltage, temperature, humidity, and/or irradiance related tothe solar cell. In some embodiments, the processor 1810 may then make adetermination for the solar cell. Examples of such determinations maycomprise, but are not limited to, leaving the solar cell intact,bypassing the solar cell, bypassing and reconfiguring the solar cell,reconfiguring solar cell strings, and/or create solar cell forecastinginformation.

As such, the processor 1810 of the control system 1800 of FIG. 18 maynot change the state of a solar cell and, as a result, the solar cellmay be left in a series string with other solar cells. The processor1810 may bypass at least one solar cell. For example, the processor 1810may receive current and voltage measurements related to one solar cell.The processor 1810 may determine that the current and voltagemeasurements are out of specification for the solar cell and thus bypassthe solar cell, as described above. Moreover, the processor 1810 maydetermine to bypass the solar cell, but to reconfigure the programmableinterconnect fabric so that energy generated from the bypassed solarcell is collected onto a parallel bus, as described above in furtherdetail. Additionally, the processor 1810 may reconfigure solar cells andthe programmable interconnect fabric such that solar cells of certainoperating performance are connected in series with other solar cells ofsimilar operating performance, as discussed in further detail above. Theprocessor 1810 may also further record a solar cell's measurements astaken over time. As such, the processor 1810 may review the historicalperformance of a solar cell and through the use of processing algorithmsmay forecast a time bounded behavior of the solar cell. For example, theprocessor 1810 may forecast the approximate operating lifespan of thesolar cell and when the solar cell will approximately fail or reach acertain threshold.

In some embodiments, other electronics may be implemented into ajunction box coupled to the back sheet in order to provide direct accessand management of the solar cells. For example, a Direct Current toDirect Current (DC-to-DC) converter may be included to provide anindependent operation of a solar cell with respect to a solar cellstring. Additional electronics may be included to process the output ofthe solar cells directly, such as converting to Alternating Current (AC)at the solar cell level, and delivering energy to an output. As such, avariety of electrical components and equipment may be used to performthe monitoring and reconfiguring of the solar cells installed on theback sheet.

In some embodiments, the memory bank 1830 may comprise amachine-readable medium able to store data temporarily or permanentlyand may be taken to include, but not be limited to, random-access memory(RAM), read-only memory (ROM), buffer memory, flash memory, and cachememory. While the memory bank 1830 may comprise a single medium, thememory bank 1830 may comprise multiple media (e.g., a centralized ordistributed database, or associated caches and servers) able to storeinstructions and/or data. The term memory bank 1830 may be capable ofstoring instructions or data (e.g., software) for execution by a machinesuch as the processor 1810, such that the instructions or data, whenexecuted by the processor, cause the processor 1810 or control system1800 to perform any one or more of the methodologies described herein.The memory bank 1830 may comprise, but not be limited to, a datarepository in the form of a solid-state memory, an optical medium, amagnetic medium, or any suitable combination thereof.

FIG. 19 illustrates an example embodiment of an embedded softwarearchitecture 1900 for use in the monitoring and/or reconfiguring ofsolar cells. In some embodiments, the embedded software architecture1900 may be comprised within the memory bank 1830 of the control system1800. In general, the embedded software architecture 1900 may be used bythe processor 1810 to perform the monitoring and reconfiguringalgorithms.

As illustrated in FIG. 19, the embedded software architecture 1900comprises a measure module 1910, reconfigure module 1920, communicationmodule 1930, Application Programming Interface (API) 1940, and database1950. In some embodiments, the measure module 1910 measures the solarcell sensors and voltage and/or current readings from solar cells andrecords the measured data and readings through the use of the API 1940and a consistent data model. The data is then accessed by thereconfigure module 1920 by using the API 1940 to build a set of learningalgorithms that may determine how the reconfiguration may occur. Thereconfiguration information from the reconfigure module 1920 is thenpassed to a cross bar switch (not shown) in the control system 1800,which may perform the various interconnect connections or disconnectionsbetween solar cells to build the solar cell strings within the solarcell matrix of the back sheet dynamically. The database 1850 maycomprise detailed data about the measurements and readings with regardto individual solar cells. For example, the database 1850 may comprisehistorical measurements with regard to a solar cell's current, voltage,irradiance, humidity, and/or temperature conditions. In someembodiments, the database may comprise an initial current-voltage (IV)curve captured at the manufacturing process. This initial IV curve maythus serve as an initial baseline characteristic. Through the operatinglife of the solar cells, the solar cell's current, voltage, irradiance,humidity, and/or temperature conditions may be recorded and/ortimestamped within the database 1950 at each point in time that themeasurements are taken. As such the database 1950 may comprise thehistorical conditions of each solar cell. Thus, the embedded softwarearchitecture 1900 may analyze the stored historical conditions anddetermine or predict a failure occurrence of a solar cell before thefailure actually occurs. For example, the embedded software architecture1900 may observe deviations from initial baseline characteristics andthus forecast an eventual failure occurrence for the solar cell. As aresult, the failure forecasting may make it possible to performproactive maintenance of the solar cells as opposed to an unplannedmaintenance of the solar cells and to manage just-in-time inventory.

FIG. 20 illustrates a flow diagram for a method 2000 of manufacturing atiled solar cell. As illustrated, at block 2010, encapsulated solarcells are assembled to at least one glass layer. In some embodiments,the solar cells are encapsulated and sealed by an EVA material and theglass is a low iron (low Fe) glass layer. As such, the encapsulatedsolar cells are assembled to the low Fe glass layer. Next, at block2020, a wire bonder assembles the solar cell package comprising theassembled encapsulated solar cells and glass. At block 2030, the solarcell package is laminated. In some embodiments, the lamination is donevia a single thermal cycle on a laminator. As such, in some embodiments,a tiled solar cell has been created after block 2030. At block 2040, insome embodiments, a tiled solar cell is tested and sorted. The tiledsolar cell may be tested to see whether it meets a predefinedmanufacturing characteristic(s). For example, the tiled solar cell maybe tested to determine whether the tiled solar cell comprises a 100%output efficiency. If the tiled solar cell does not comprise such anefficiency, then it may be sorted out and replaced with another tiledsolar cell comprising an ideal output efficiency.

FIG. 21 illustrates a flow diagram of a method 2100 for initializing anintelligent cleaning system for a solar power system. In general, theintelligent cleaning system may be initialized if the system detectsthat the solar cells may be soiled or dirty such that the solar cellsare not operating at a maximum performance. As such, the intelligentcleaning system may remove foreign matter. In some embodiments, theintelligent cleaning system may use water or a water based solution toremove the foreign matter.

As illustrated in FIG. 21, at block 2110, measurements of a solar cellare received. In some embodiments, the measurements of a solar cell maycomprise, but are not limited to, current, voltage, humidity,irradiance, and/or temperature of the solar cell. At block 2120, themeasurements may be processed and the current solar cell characteristicsmay be compared to historical trends of the solar cell'scharacteristics. For example, IV characteristics of each solar cell maybe compared to the solar cell's historical IV characteristics. As such,if the current IV characteristics show a deviation from historicaltrends, then the solar cell may be partially covered by foreign matterthat is reducing the solar cell's performance and thus its IVcharacteristics. At block 2130, a determination is made whether it canbe inferred that foreign matter is at least partially covering a solarcell. In some embodiments, the intelligent cleaning system may utilize aweather sensor in conjunction with analyzing the historical trends of asolar cell's characteristics in order to determine whether the systemmay infer that foreign matter exists on the solar cell. For example, aweather sensor may indicate particularly heavy cloud cover in thevicinity of the solar cell. As such, the solar cell performance andcharacteristics may suffer due to the cloud cover preventing sunlight orother light sources from reaching the solar cell. In such a case, theintelligent cleaning system may infer that the degradation in the solarcell's performance or characteristics is due to the weather and not dueto foreign matter being present on the solar cell. As such, at block2150, the intelligent cleaning system is not initialized if it isdetermined foreign matter or soiled conditions are not present withrespect to the solar cell. However, at block 2140, the intelligentcleaning system is initialized if it is determined or inferred thatforeign matter exists on the solar cell.

In some embodiments, measurements from an irradiance sensor andhistorical trends in solar cell outputs may be used to determine orinfer whether foreign matter exists on the solar cell. For example, thesystem may monitor the output level of the solar cells and notice thatthe output level has decreased from an expected output level. In someembodiments, the expected output level may be computed from themeasurements of the irradiance sensor and/or expected solar cell output.The system may analyze the irradiance sensor output and historicaltrends in the solar cell data. As such, the intelligent cleaning maywash the solar cell with a fluid in order to remove the foreign matter.In some embodiments, the system may group solar cells and perform theabove monitoring and computing processes as described above for everysolar cell in a group.

In some embodiments, the method 2100 of FIG. 21 may measure an I/V(current/voltage) output for each solar cell in the solar cell array.The insolation at the site of the solar cell array may be measuredthrough an external pyranometer. Based on the insolation or irradiance,the expected I/V for each solar cell is computed. In some embodiments,the expected I/V may be computed based on the initial I/V of the solarcell at the time of manufacturing. If the measured I/V of a solar cellunder insolation deviates from an expected I/V of the solar cell, thenthere may be a shadow on the solar cell or foreign matter may exist onthe solar cell. In some embodiments, the system may track the I/V of thesolar cell over a period of time. For example, if the I/V of a solarcell changes over a few hours, then the loss in performance or I/V ofthe solar cell is likely due to a shadow present on the solar cell. Insome embodiments, the I/V loss may be measured over two consecutive daysin order to check whether the performance loss occurs at the same timeand magnitude with the same step loss. In some embodiments, thedetection of a shadow may issue an alert such that corrective action maybe made to prevent loss of performance due to the shadow. Otherwise, ifthe loss in performance of the solar cell is constant over a period oftime, then the loss in performance may be due to foreign matter beingpresent on the solar cell. In this case, a cleaning system may betriggered.

FIG. 22 a illustrates an installation 2200 of conventional solar modulesonto a surface. As illustrated, the installation 2200 comprises theplacement of solar modules 2220 and 2230 onto a surface (e.g., a parcelof land) 2210. The solar modules 2220 and 2230 comprise identical fixeddimensions as defined in the design and manufacturing process of thesolar module. For example, each solar module 2220 and 2230 comprises adimension 2221. However, as is evident, the dimension length 2221 ofeach solar module 2220 and 2230 is significantly larger than the length2241 of the segment 2240 of the surface 2210. As such, neither of thesolar module 2220 nor the solar module 2230 may be installed into thesegment 2240. Thus, when conventional solar modules are used, a portionof the surface 2210 is unused.

FIG. 22 b illustrates an example embodiment of the installation 2270 ofa back sheet with tiled solar cells onto the same surface 2210. In someembodiments, the surface 2210 may comprise, but is not limited to, aparcel of land, a roof of a building, exterior of a building orstructure, a hill side, sloped terrain, and/or any curved surface. Asillustrated, the installation 2210 comprises the placement of tiledsolar cells 2250 onto the surface 2210. As is evident, the tiled solarcells 2250 comprise smaller dimensions than the conventional solarmodules 2220 and 2230 and the dimension 2241. As such, the tiled solarcells 2250 may be placed into the surface segment 2240. As a result, thetiled solar cells 2250 may be installed on more of the area of thesurface 2210. Since the tiled solar cells 2250 may be placed into thesurface segment 2240, then the installation of a system using the tiledsolar cells 2250 may produce more energy than a system using theconventional solar modules 2220 and 2230 due to the increased groundcoverage.

As discussed earlier, a back sheet may comprise a current carrying grid,programmable interconnect, and cell tiles into which tiled solar cells2250 may be inserted. As such, the back sheet may be placed into thesurface segment 2240 and the rest of the surface 2210. In someembodiments, the back sheet may be configured or implemented such thatthe back sheet fits into the contours, dimensions, and/or shape of thesurface 2210. As such, the back sheet may be placed onto a curvedsurface or a surface with irregular dimensions. Tiled solar cells 2250may then be inserted into the back sheet in order to create a solarpower system comprising tiled solar cells that cover much of anavailable surface.

FIG. 23 illustrates a flow diagram of a method 2300 of installing a backsheet with tiled solar cells in accordance with some embodiments of thepresent invention. The method 2300 starts, at block 2310, by determiningthe land or surface characteristics to which the back sheet with tiledsolar cells will be installed. For example, the land or surfacedimensions, contours, and/or shape may be determined. In someembodiments, voltage output standards for the land or surface may alsobe determined. At block 2320, the back sheet is arranged or configuredto match the land or surface characteristics. For example, the backsheet may be configured so as to spread and cover across a roof. In someembodiments, the back sheet may be arranged to fit into irregulardimensions of a surface area or parcel of land. In other embodiments,the back sheet may be arranged or configured such that the cell tiles ofthe back sheet produce a voltage needed by an inverter. For example, theback sheet or solar cell strings may be arranged to produce voltageoutputs of 1200 volts or 2000 volts. At block 2330, the back sheet isplaced onto the land or surface. Next, at block 2340, tiled solar cellsmay be inserted into the cell tiles of the back sheet. In someembodiments, the tiled solar cells may be inserted into the cell tilesof the back sheet before the back sheet is placed onto the land orsurface.

Additional Advantages of the Back Sheet with Tiled Solar Cells

An implementation of the back sheet with tiled solar cells providesnumerous advantages over a conventional system comprised of solarmodules that house solar cells. For example, each solar cell in thetiled solar cell receives the same protection as it would from beinghoused within a conventional solar module. As such, individual tiledsolar cells may be mass produced with few additional steps in a cellmanufacturing plant. The elimination of the solar module results insavings from the lack of module manufacturing costs. For example, theback sheet with tiled solar cells does not require a tabbing andstringing process as is done in the manufacturing of solar modules. Assuch, costs in acquiring tabbing and stringing equipment may not benecessary for the manufacturing of the back sheet and tiled solar cells.Moreover, large format glass costs are eliminated as each individualtiled solar cell may comprise a smaller format glass layer when comparedto the large format glass layer of a solar module. Transportation costsfor the tiled solar cells and back sheet would also be less whencompared to conventional solar modules since the tiled solar cells maybe packaged into containers and may comprise a lower weight, lesseryield costs due to reduced breakages, lower wiring costs due to thecompactness of solar cells, and less or no DC cables forinterconnections. The back sheet may also comprise a variety of lengthsor sizes (and thus implemented with various numbers of tiled solarcells) as compared to a conventional solar module that is of a fixedlength or size. As such, the back sheet with tiled solar cells mayresult in lower land costs as the back sheet with tiled solar cells maycomprise a higher packing density of solar cells relative to theconventional solar module.

Since the solar cells are comprised within individually tiled solarcells that are implemented on a back sheet, the back sheet and/or tiledsolar cells may be placed onto land with varying dimensions or on curvedcontours. As such, the back sheet with tiled solar cells provides moreflexibility in the mounting of the solar power system on different typesof surfaces or land. This may result in an increased ground coverageratio.

The system comprising a back sheet and tiled solar cells would alsocomprise easier installation and maintenance as well as more costeffective installation and maintenance. For example, the tiled solarcells may be easily dismounted from mechanical holders attached to theback sheet. As such, the tiled solar cells may be easily replaced. Thus,if a single tiled solar cell is not functioning at a certainspecification, then the single tiled solar cell may be removed insteadof an entire conventional solar module being removed. As a result,maintenance and installation costs for tiled solar cells may besignificantly lower than that of replacing a solar cell housed within aconventional solar module.

The systems, circuits, and methods disclosed herein also provide easierthermal management. As the tiled solar cells are individually exposedand not sealed inside a conventional solar module, the heat that maydevelop through sun exposure may be thermally managed away through theuse of fins, heat sinks, and other heat dissipation techniques.

As discussed above, the systems, circuits, and methods disclosed hereinalso provide the monitoring and reconfiguring at the solar cell level.This finer level of granularity, when compared to granularity at theconventional solar module level, provides a more robust and efficientsystem

Applications for Embodiments

The current disclosed embodiments may be targeted by variousapplications. For example, such applications may comprise, but are notlimited to, solar cell level monitoring, solar cell level reconfiguring,data logging of solar cell characteristics, in-situ testing of solarcells during the manufacturing process, and intelligent cleaning systemsfor solar power systems.

A solar cell level monitoring application may comprise each solar cellin the back sheet being measured and tracked under varying conditions oftemperature, humidity and irradiance. Each solar cell may also bemonitored with respect to its voltage and/or current. With the moredetailed granularity level of monitoring at the solar cell level, asolar cell monitoring application may understand and determine solarcell aging and degradation, develop models to forecast a failure modefor the solar cell or approximately when the solar cell will fail. Theseforecasts may assist with proactive maintenance and just-in-timeinventory management. Moreover, the solar cell monitoring applicationmay be able to infer soiling and shading conditions. For example, thesolar cell monitoring application may develop a historical record of asolar cell's operating performance and characteristics. If the solarcell is functioning out of specification, then the solar cell monitoringapplication may be used to determine whether the solar cell has degradedto below specifications or if temporary soiling and shading conditionsare responsible for the degradation in the performance of the solarcell.

A solar cell level reconfiguring application may comprise solar cellstrings that are dynamically built and re-built to react to changingambient conditions of solar cells in real time. This reconfiguration ofsolar cell strings allows for optimizing solar cell string performanceto maximum power point tracker (MPPT), match voltage specifications, andto re-build the solar cell strings to avoid the negative impact ofshaded, soiled, or degraded solar cells.

A data logging application may comprise measured data of solar cellsbeing saved in a database for extended periods of time. This recordedinformation may then be used for various types of analyses of the solarcells, such as root cause failure analysis

An in-situ testing of solar cells application may occur during themanufacturing and assembling process. In some embodiments, after thetiled solar cells have been placed on the back sheet forinterconnection, an in-situ testing step may be performed to check eachtiled solar cell in the tiled solar cell string in order to ensure thatthe tiled solar cell is operating within specifications. If there is anytiled solar cell that exhibits abnormal behavior within the tiled solarcell string, then that tiled solar cell may be easily replaced by afunctioning tiled solar cell.

An intelligent cleaning system application may comprise a more efficientcleaning system for solar power systems. The ability of the softwarealgorithms discussed above may infer when a solar cell has been shadedor soiled by foreign matter. As such, it would be possible to integratea cleaning system that turns on only when needed to clean the solarcells and to effectively remove the foreign matter from the solar cells.This integration will result in the conservation of cleaning fluid, suchas water, as the cleaning fluid is only used when foreign matter isshading a portion of a solar cell and inhibiting overall solar cellperformance.

Although the present invention has been described in terms of specificexemplary embodiments, it will be appreciated that various modificationsand alterations might be made by those skilled in the art withoutdeparting from the spirit and scope of the invention. The previousdescription of the disclosed embodiments is provided to enable anyperson skilled in the art to make or use the present invention. Variousmodifications to these embodiments will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other embodiments without departing from the spirit or scopeof the invention. Thus, the present invention is not intended to belimited to the embodiments shown herein, but is to be accorded thewidest scope consistent with the principles and novel features disclosedherein.

1. A system for monitoring solar cells on a back sheet, the systemcomprising: an interconnect circuit on the back sheet forinterconnecting a plurality of solar cells so as to provide an array ofindividually addressable solar cells; and a monitoring circuit, coupledto the interconnect circuit, for monitoring one or more conditions atthe individually addressable solar cells.
 2. The system for monitoringsolar cells as set forth in claim 1, wherein the monitoring circuitcomprises at least one temperature sensor.
 3. The system for monitoringsolar cells as set forth in claim 1, wherein the monitoring circuitcomprises a sampling circuit for sampling a voltage level at each of thesolar cells as a function of time with a certain periodicity andinterval between samplings.
 4. The system for monitoring solar cells asset forth in claim 1, wherein the monitoring circuit comprises at leastone humidity sensor.
 5. The system for monitoring solar cells as setforth in claim 1, wherein the monitoring circuit comprises at least oneirradiance sensor.
 6. The system for monitoring solar cells as set forthin claim 1, wherein the monitoring circuit samples the solar cells byusing a clocking scheme to walk through all each of the solar cells in arow of selected solar cells.
 7. The system for monitoring solar cells asset forth in claim 1, wherein a current-voltage (IV) characteristic ofat least one of the solar cells is measured and stored in a databasecomprising a historical IV characteristic trend of the solar cell.
 8. Amethod for monitoring solar cells on a back sheet, the methodcomprising: interconnecting a plurality of solar cells so as to providean array of individually addressable solar cells; and monitoring, by amonitoring circuit coupled to an interconnect circuit, for monitoringone or more conditions at the individually addressable solar cells. 9.The method for monitoring solar cells as set forth in claim 8, whereinthe monitoring circuit comprises at least one temperature sensor. 10.The method for monitoring solar cells as set forth in claim 8, whereinthe monitoring circuit comprises a sampling circuit for sampling avoltage level at each of the solar cells as a function of time with acertain periodicity and interval between samplings.
 11. The method formonitoring solar cells as set forth in claim 8, wherein the monitoringcircuit comprises at least one humidity sensor.
 12. The method formonitoring solar cells as set forth in claim 8, wherein the monitoringcircuit comprises at least one irradiance sensor.
 13. The method formonitoring solar cells as set forth in claim 8, wherein the monitoringcircuit samples the solar cells by using a clocking scheme to walkthrough each of the solar cells in a row of selected solar cells. 14.The method for monitoring solar cells as set forth in claim 8, wherein acurrent-voltage (IV) characteristic of the solar cells is measured andstored in a database to comprise a historical IV characteristic trend ofthe solar cells.
 15. A system for monitoring solar cells, the systemcomprising: a back sheet comprising an interconnect circuit forinterconnecting a plurality of solar cells, the interconnect circuitcoupled to each of the solar cells and at least one sensor; and amonitoring circuit, coupled to the interconnect circuit, for receivingsignals from the solar cells and the sensor and for determining at leastone condition at the solar cells.
 16. The system for monitoring solarcells as set forth in claim 17, wherein the monitoring circuit comprisessampling accuracy tuned for a specific monitoring application.
 17. Thesystem for monitoring solar cells as set forth in claim 17, wherein themonitoring circuit comprises a sampling circuit for sampling a voltagelevel at each of the solar cells as a function of time with a certainperiodicity and interval between samplings.
 18. The system formonitoring solar cells as set forth in claim 17, wherein the monitoringcircuit enables a row of the solar cells such that the enabling allows avoltage to be measured across each of the enabled solar cells.
 19. Thesystem for monitoring solar cells as set forth in claim 17, wherein thesensor comprises at least one irradiance sensor.
 20. The system formonitoring solar cells as set forth in claim 17, wherein the sensorcomprises at least one temperature sensor.